1. Field of Invention
The present invention relates generally to the field of electronics device packaging. More specifically, the present invention is related to a method and apparatus for vibration and shock isolating electronics while maintaining optimal thermal performance as provided by the direct couple heat source to heat sink approach.
2. Discussion of Prior Art
Displays and computers employed in mission critical shipboard applications must be ruggedized to an extent that they can remain operational after very violent shock and vibration events. These events can occur during combat because of weapon strikes or during any other potentially catastrophic system failure. When these events occur it is vital that critical systems on the ship remain operational. Therefore, the U.S. government has established testing guidelines that simulate these events to ensure that vital electronics are properly designed to meet the requirements. One example standard is MIL-S-901D. There are other similar standards in other countries.
In order to pass the required tests to meet MIL-S-901D requirements, most electrical systems need some mechanical protection to limit the degree of shock energy transferred to the components or to strengthen the components sufficiently to survive the energy transferred. Known methods to do this include vibration isolation mounting, rigid encapsulation with sealants or adhesives, heavy mechanical braces & mounting, or combinations of these methods. FIGS. 1A-B show a prior art example of internal vibration mounting with internal shock/vibration mounts 10.
These methods all have disadvantages including added weight, cost, and often they increase total footprint of the components being protected. Many times, the internal space required for isolation mounts makes the outside enclosure size unacceptably large for the target application.
An additional drawback to the internal shock mounting approach is that it is much harder to transfer the heat from high power components to the outside of the case when the components are shock isolated. Only convection cooling methods can practically be employed. If any direct conduction cooling approaches are attempted, the design runs the risk of transferring significant shock energy to the components.
Another technique often employed is to shock isolate the entire sub-assembly, in this case the entire display. In this approach, the scheme to mount the display into the final application is significantly burdened by increased size, weight, complexity and additional cost. This approach does, however provide shock/vibration protection to the electronics while still allowing the electronics to be directly coupled to the external enclosure for better heat dissipation. FIGS. 2A-C show a prior art example of external shock mounting with external shock/vibration mount 20.
U.S. Pat. No. 7,254,014 to Cancellieri et al. describes a housing for display electronics with gaskets to provide shock protection and cooling fins on the rear of the assembly. However, Cancellieri et al. do not implement or suggest a floating sub-assembly to protect the internal electronics from shock while simultaneously providing excellent heat transfer to the exterior of the enclosure.
U.S. Pat. No. 7,447,034 to Shin describes a sheet of heat conducting material used to isolate any vibrations induced by the electronics from the rest of the case, while still promoting good heat flow to the external case. However, the electronics are still rigidly mounted to the “chassis” base which is then directly mounted to the case of the unit.
Whatever the precise merits, features, and advantages of the prior art, none of them achieves or fulfills the purposes of the present invention.